How to make sure your tyre tread depth is not illegal

November 26, 2021

How To Make Sure Your Tyre's Tread Depth Is NOT Illegal

Your tyres are the only part of your car that touches the road. Without them, you won't be able to go anywhere.

Your tyre tread is what grips whatever surface you are driving in - be it a smooth paved road or a rough and rocky dirt trail.

So what happens when your tread starts to wear down?

In this article, we'll discuss your tyre tread depth: what it is, its importance, and how to ensure your tread depth is still considered street legal.

What is tyre tread exactly?

Tyre tread is the rubber found on the circumference of your tyre. It is the part of the tyre that comes into contact with whatever surface you are driving on - from smooth highways to muddy off-road terrains.

How to make sure your tread depth is not illegal

Why is tyre tread important?

Your tyre tread is what grips the driving surface, keeping your vehicle steady so you don't lose control. Tyre tread also helps to:

  • Keep your car on the road.

  • Drain water so your tyre stays dry to avoid any accidents.

  • Enhance grip and traction for safe braking and confident driving.

What is Tyre Tread Depth?

Tread depth is how much tread you have left on your tyre and is measured in millimetres in Australia.

When a tyre is brand new, it starts off with about 8mm of tread depth - measuring from the bottom surface of the tyre to the top of the tread.

However, since your tyre is always in constant friction with the road, the tread will eventually wear down.

As the tread depth gets shallower, going down from 8mm to 5mm to 3mm and so on, your tyre will lose its ability to grip and stay on the road.

What is the legal Tyre Tread Depth in Australia?

In Australia, the legal minimum tread depth for passenger car tyres is 1.6mm. This applies to the central three-fourths area of a tyre's circumferential tread and across its entire circumference, all the way around.

TAKE NOTE: Tyre manufacturers recommend that you don't allow your tyre tread depth to go below 3 mm for added safety.

Tyre tread depth chart

What happens when my Tyre Tread Depth is below the legal limit?

Anything below 1.6mm is considered illegal in Australia. If caught driving an illegal tyre, you will receive a fine and demerit PER TYRE below the legal limit- which varies per state/territory.

It is also dangerous to drive because:

  • Your tyre will lose grip and traction.

  • It will take longer for your brakes to stop the car on wet surfaces.

  • Increased aquaplaning risk

  • Higher chances of blowouts.

  • Any accidents caused by illegal tyres may not be covered by your insurance company.


​​How to measure your Tyre Tread Depth

There are three main ways of measuring/checking your tyre tread depth.

1. The 20c test

Take a 20c coin and check out the swimming platypus because he will do the checking for you. Insert the coin into the tread grooves on your tyre. If you can see the entire platypus bill and your tread doesn't reach or cover it, replace your tyre ASAP. We recommend you take the 20c test once a month and before any road trips.

Tyre 2c test

2. Check the Tyre tread wear indicators

Tread wear indicators are little raised notches of tread moulded into your tyre's tread grooves. They are placed by manufacturers to help ensure your safety on the road.

When your tyre tread wears down and becomes flush with these indicators, your tyre has reached the limit of its safety. It's time to get a new set of tyres to avoid possible blowouts and accidents. ​Make it a habit to check them once a month.

Tyre 2c test

3. Use a tyre tread depth gauge

A tyre tread depth gauge is a handy measuring tool that you can use to measure the tread depth of an individual tyre.

Tyre 2c test

What speeds up your tyre's tread wear?

Though your tyres will really wear out over time, there are some factors that can accelerate the process. Some examples include:

   1. Where you frequently drive

   2. Your personal driving style

   3. Incorrect tyre pressure

   4. Driving frequently with excess weight

   5. Misaligned wheels

   6. Overspeeding - especially when cornering

   7. Steering and suspension issues

   8. Defective brakes

How to ensure your Tyre Tread Depth is always within the legal limits?

To check your vehicle’s tyre tread wear, you may refer to the following ways:

  • Inspect your tyres monthly for tread depth, proper tyre inflation, and any damage.

  • If your tread depth is less than 3mm, you should consider replacing your tyres.

  • Regularly get your tyres rotated to ensure even tread wear.

  • Get your wheels professionally aligned (every six months).

If your tyres are about to hit the legal limit, consider replacing them with a new set from Tyroola. We have tyres to fit all your driving needs and all budgets.

Start shopping for your new tyres HERE.